Apparatus for tightening and strapping involutely wound sheet metal coils



nited States Patent [72] Inventors Paul W. Lehmann Mulheim-Ruhr, Germany; Johan N. H. van Hoeyen,'Beek-Gemeinde a corporation of Delaware [54] APPARATUS FOR TlGl-[TENING AND STRAPPING INVOLUTELY WOUND SHEET METAL COILS 5 Claims, 2 Drawing Figs.

3,225,683 12/1965 Rhea 100/4 3/ l 966 Patterson 100/3 3,252,408 5/1966 Winkler 100/26 3,315,592 4/1967 Lems 100/3 3,320,874 5/1967 Gasperetal.... 100/3 3,329,083 7/1967 Bellmann 100/3 3,379,121 4/1968 Lems 100/2 3,417,688 12/1968 Shakely l00/26X Primary Examiner-Billy J. Wilhite AttorneyEdward R. Lowndes ABSTRACT: An apparatus for tensioning a loop of strapping about a vertically disposed involutely wound coil while at the same time shifting the outermost coil convolution in a coil tightening direction. A vertically shiftable carriage supports a circular strap chute so that it is concentric with the vertical coil axis. A strapping head mounted on the carriage feeds strapping to the chute and is movable radially toward and away from the coil. The carriage is capable of angular turning movement in a coil-tightening direction about the axis of the coil during the strap tensioning operation so that the strap loop will carry the outermost coil convolution in a coil tightening direction and draw the coil tight prior to the strap serving and seal-applying operation. A vertical lift for the coil is provided and operates, when a short coil is undergoing strapping, to elevate the coil to the level of the strap chute, thus avoiding ground interference with the strapping head.

Patented Oct. 13, 1970 Sheet of 2 Fig.7 7 48 INVENTORS: PAUL ,w. LEHMANN JOHAN N.H van HOEYEN By: Q

Patented Oct. 13; 1970 3,533,351

Sheet 2 of 2 Fig. 2

INVENTOR. PAUL W. LEHMANN JOHAN N-H. von HOEYEN The present invention relates to apparatus for applying a strap to an involutely wound sheet metal coil at the strapping station of a strapping machine and, simultaneously with the strapping operation, tightening the coil convolutions so that the adjacent convolutions of the completely wound coil will be in intimate contiguity, thus rendering the coil solid.

Heretofore, considerable difficulty has been encountered in the effective strapping of relatively massive coils at a strapping station due to the fact that the outermost few convolutions of the coils are not tight. The problem is particularly acute where hot coils are delivered to the strapping station direct from the rolling mill and, in such condition, they cannot conveniently be handled. Although the inner convolutions of such coils may be tight, invariably the last few outermost coil turns are loose due to the normal tendency of the coils to unwind. With a coil of this nature, the conventional application of a strap thereto may serve to bind the extreme outermost coil convolution to the next adjacent convolution, or at the most, to bind the three outermost convolutions to one another. However, these outermost turns are not tightly bound to the remaining inner convolutions so that when the strap has been severed and the conveyor transports the coil away from the strapping station, the joggling motion of the conveyor will cause an inward unwinding of these outer coil turns and a condition of equilibrium will obtain where the tightness of the outer coil turns will be dissipated radially back into the coil and the applied strap will become loose and fall to the bottom rim of the coil. Subsequently, when the coil is lifted by a conventional coil grab, the coil will shed its strap and be transported in an unstrapped condition.

Various methods of coil tightening have heretofore been employed, both preparatory to and during the coil strapping operation. Coil lubrication and coil vibration in an effort to cause natural settling of the coil convolutions during the strap tensioning operation has proven effective only where extremely small coils are concerned, where coil temperatures are low, and where smooth sheet metal surfaces are involved.

Where automatic strapping machine operations are concerned and embodying relatively massive hot sheet metal strip coils, coil tightening has been accomplished by bodily turning or orbiting the entire strapping machine or head in a coiltightening direction about the central axis of the coil at such time as the strap has been tensioned and before the seal has been applied or the strap severed. The tensioned strap will thus, due to friction, carry the outermost coil convolution with which it is in intimate contact in a coil-tightening direction so that when the coil is fully tightened, the strap, still tensioned, may then be severed. Such a procedure, although widely used at the present time, is possessed of certain limitations from the point of view of both machine design and machine function.

Insofar as machine design is concerned, the provision of arcuate guide rails or tracks for oscillation of the strapping machine and of power equipment for causing such oscillation is costly. Furthermore, with fixed arcuate guide rails, a given machine is incapable of effectively operating upon coils which vary appreciably in diameter. Thus, each machine must be designed for the strapping of coils having a specified diameter. For example, where such a machine is put to use in the strapping of a coil of lesser diameter than that for which the machine is intended, the strapping head will travel in a curved path of large radius and which does not follow the curvature of the coil but rather is tangential to the coil, thus pulling the strapping loop away from the coil in the immediate vicinity of the strapping head thereby exposing a limited area of the outermost coil convolution which is then free to buckle outwardly away from the next innermost coil convolution. When tensioning of the strap has been completed and the strap is finally severed, the material of the buckle will dissipate itself back into the inner regions of the coil and reestablish a condition of coil looseness.

The present invention is designed to overcome the above noted limitations that are attendant upon the construction and use of strapping machines which operate to perform the dual function of both tightening and strapping relatively large sheet metal coils and, toward this end, the invention contemplates the provision of such a machine wherein the use of arcuate guide rails is eliminated and, instead, the strapping head is carried on a rotatable carriage which is capable of turning movement about the vertical axis of the coil undergoing tightening and strapping. The strapping head is equipped with the usual strap feeding chute which conducts the strapping in a circular path around the coil at the level of the strapping head and thus, in order to apply the strap to the coil at the desired level (which usually is on the horizontal centerline of the coil) means are provided for raising and lowering the carriage to bring the strapping head and chute to such desired level. This raising and lowering of the carriage is also resorted to for clearance purposes so that by raising the carriage to its uppermost position a strapped coil may be conducted horizontally from the strapping station and a new coil conducted horizontally to the strapping station without interference from any part of the strapping instrumentalities. In order to reduce the height to which the supporting carriage for the strapping head and chute must be raised to accommodate relatively tall" coils, i.e. coils of large axial extent, means are provided for conducting the coils to the strapping station at a low level and thereafter elevating the individual coils to a convenient strapping level at which strapping takes place and for thereafter restoring the coils to such low level for conduction from the strapping station. This means for raising and lowering the coils individually also facilitates the effective strapping of extremely short coils and the proper placement of the straps therearound since, in the absence of such means, there would be insufficient ground clearance to permit low level strapping. Such vertical coil shifting also makes possible the application of multiple straps to any given coil with the lowermost strap being positioned near the lower rim of the coil if desired. A further advantage of the coil-elevating means resides in the fact that when a coil of relatively small diameter is undergoing strapping, the strapping operation takes place above the level of the conveyor or other coil supporting device which, otherwise, would interfere with the normal inward movement of the strapping head during the strap tensioning operation.

The provision of a strapping apparatus such as has briefly been outlined above constitutes the principal object of the present invention. Other objects and advantages, not at this time enumerated, will become apparent as the following description ensues.

In these drawings:

FIG. 1 is a side elevational view, somewhat schematic in its representation, of a coil tightening and strapping apparatus embodying the present invention; and

FIG. 2 is a slightly enlarged plan view of the structure shown in FIG. 1 and with the parts in a different position.

Referring now to the drawings in detail, the invention is described herein in connection with a production line of hot steel strip coils leading to a strapping station S, the coils being brought, one at a time and successively, to the station on an intermittently movable conveyor 10. The conveyor is preferably of the dual chain type and includes a pair of conveyor chains 12 which travel on respective supporting rails 14 and are driven in unison. The portions of the conveyor frame which pass through the strapping station S are supported on a horizontally disposed base frame 15 which, in turn, is supported on pillars 16 from the floor or other supporting surface 17. The base frame 15 is comprised of longitudinal side members l8, and transverse cross members 20.

The base frame 15 serves to support a vertically disposed column assembly 22 which embodies a pair of structural channel members 24, the open sides of which face inwardly toward each other and which are connected together by cross members 26. The column assembly 22 serves to slidably support a carriage 30 which is shiftable vertically under the control of a fluid-actuated hoist between the operative lowered strapping position wherein it is shown in full lines in FIG. 1 and the raised inoperative position shown fragmentarily in dotted lines in this view.

The carriage 30 includes a body portion 32 from which there projects forwardly a jib 34, the distal end region of which projects into the strapping station S. The carriage 30 is guided in its vertical movements by means of a pair of upper rollers 36 and a similar pair of lower rollers 38, the various rollers being confined between opposed rails 40 which are mounted in the inner sides of the channel member flanges. The vertical shifting movements of the carriage 30 are effected under the control of a fluid-actuated hoist including a piston and cylinder assembly 41 which extends between the frame 15 and carriage 31) and includes a cylinder 42 connected to the frame 15 and a plunger 43 connected to the carriage 30. Fluid parts 44 and 45 for operating the piston and cylinder assembly are provided at the opposite ends of the cylinder 42. The weight of the carriage 34 is counterbalanced by means of a series of weights 45 which are confined in a boxlike enclosure 47 at the rear of the frame 15, the weights being connected to the jib 34 by a cable 48 which passes over a pair of rollers 50 mounted on a bracket 52 carried at the upper end of the column assembly 22.

At the outer end of the jib 34 there is provided a bearing support 54 for a horizontally rotatable elongated frame 56. The frame 56 is comprised of two channel members 60 the open sides of which face toward each other and which are connected together at their opposite ends by spacer bars 62 and 64. The medial regions of the channel members 60 are connected together by a rectangular plate 66, the latter being supported from the bearing support 54. A plate 67 is provided at the end of the frame 56 adjacent the spacer bar 62.

Suspended from the channel member 60 by means of vertical struts 68 is a circular strap guide or chute 70, the radius of curvature of which is appreciably larger than the diameter of the largest coil capable of being strapped at the strapping station, the function of the chute being to guide a length of steel strapping material in an arcuate path around the coil to form a loop which is subsequently tensioned about the coil in a manner that will be described in detail presently. The strap chute 70 is of channel shape in cross section and is so disposed below the frame 56 that it is concentric with the vertical axis of the bearing support 54 and with the vertical axis of a coil undergoing strapping. The continuity of the strap chute 70 is interrupted at a region immediately below the frame 56, thus presenting a feed inlet end 72 for endwise reception of the lead end of the strapping material, and a return or outlet end 74 for such lead end, it being understood that the strapping materials will be fed from and tensioned by' a conventional strapping head such as has been designated in its entirety at Various commercial strapping heads having strap-feeding, strap-tensioning, seal-applying and strap-severing instrumentalities associated therewith are available for use in connection with the present strapping system to accomplish the aims of the invention. However, the particular strapping head selected for illustration herein is of the general type shown and described in U.S. Pat. No. 2,915,003, dated Dec. 1, 1959 and entitled Power Strapping Machine. The entire disclosure of such patent, insofar as it is consistent with the present disclosure, is hereby incorporated in and made a part of this application by reference thereto. The present disclosure of the strapping head 80 is largely schematic in its representation and embodies only the outline thereof and its positional relationship with respect to the strap chute 70.

The strapping head 80 is suspended from a horizontally shiftable carriage 82 by means ofa depending support 84. The carriage 82 is slidably supported for longitudinal reciprocation along the frame 56 by means of rollers 86 which project laterally into guideways 38 provided adjacent the opposite side edges of the frame. A cylinder 90 secured in a bracket 92 carried by the frame 56 is provided with a piston-actuated plunger 94 attached to one end of the carriage 82. The cylinder is provided with ports 96 and 98 adjacent the ends thereof which are operatively connected to a suitable control valve (not shown) by means of which the piston and cylinder arrangement may be actuated to effect reciprocation of the carriage 82.

In order to effect turning movement of the frame 56 about the axis of the bearing support 54, and consequently about the vertical axis of a coil undergoing strapping at the strapping station S, an arcuate toothed rack segment 100 meshes with a pinion 102 carried on a short vertical shaft 104 rotatable in a bearing bracket 106 suitably mounted on the jib 34. The shaft 104 is adapted to be driven in either direction by means of a reversible motor M which may be either an electric or a fluid motor, the motor being fixedly secured to the bracket 106. it will. be apparent that upon operation of the motor M in one direction or the other, the entire frame 56, including the carriage 82 which is supported thereby, will be rotated in either a clockwise or a counterclockwise direction as viewed in P16. 2. During such rotation of the frame 56, the strapping head 81) will describe an are about the axis of the bearing support 5 1 and consequently about the axis of the coil undergoing strapping in a manner and for a purpose that will be made clear presently. A pair of limit stops 108 on the rack segment limit the extreme positions of the frame 56.

Successive coils which are conducted by the conveyor 10 to the strapping station S may be strapped in situ on the conveyor if they are of sufficient height so that the strap chute may be lowered to the mid-plane of the coil. However, where a relatively short coil such as that shown in full lines at C is concerned, a fluid-actuated hoist 109 is provided for elevating the coil upwardly above the plane of the conveyor 12. Toward this end, a platform 110 is fixedly mounted on the upper end of a plunger 112 which projects into a cylinder 114 mounted on one of the cross members 20. The lower end of the plunger carries a piston (not shown) which is reciprocable in the cylinder and a pair of fluid ports 116 and 118 at the opposite ends of the cylinder control the admission of fluid to the cylinder for actuating the plunger and consequently raising and lowering the platform 110 and coil carried thereby.

In order to establish the desired strapping level for application of the loop of strapping to the coil C, a pair of identical strap supporting assemblies 120 are mounted on the frame 56. Each assembly includes an angular strap supporting'arm 122 which is movable between a projected strap-supporting position wherein the forward end thereof bears against the outer cylindrical surface of the coil C as shown in full lines in FIG. 2, and a retracted out-of-the-way. position in the vicinity of the strap chute 70 as shown in dotted lines in this view. The extreme forward end of each arm 122 carries a strap-engaging roller 124 while the other end of the arm is secured to the lower end of a vertically disposed spindle 126 from which there extends outwardly at the upper end thereof a crank arm 128. The outer end of each plunger 128 is pivotally connected to a plunger 130 associated with a cylinder 132 which is pivoted on a bracket 134 fixedly mounted on the plate 67 which extends between the two channel members 60 of the frame 56. Manifold connections 138 lead to the opposite ends of the cylinder so that the plungers 128 may be operated in unison. From the foregoing description it will be apparent that when the plungers 130 are in their retracted positions the two strap-supporting arms 122 will assume their out-of-the-way positions remote from the coil C and that when the plungers move to their advanced positions the arms 122 will swing inwardly toward the coil and come to rest against the outermost coil winding. The arms 122 are capable of swinging movements in a plane which lies immediately below the level of the strap chute 70 and they are adapted to make simultaneous contact with the coil at regions which subtend an arc of approximately 60 on the side of the coil remote from the strapping head 80 in order that during the tensioning operation the rear region of the strapping will slide over these arms while the strapping head gradually pulls the strap loop to approximately the level of the chute from which the strapping is initially released.

Considering now the cyclic operation of the coil strapping and tightening apparatus, prior to arrival ofa given coil C at the strapping station 8, fluid is supplied to the lower port 45 of the piston and cylinder assembly 41, thus projecting the plunger 43 upwardly and raising the carriage 30 and jib 34 to its uppermost position and elevating the strapping head 80 and its associated strap chute 70 to a level which is adequate to afford clearance for entry of a coil into the strapping station on the intermittently operable conveyor 10. At the same time, the motor M will be operated to rotate the pinion 102 in a clockwise direction as viewed in FIG. 2, thus driving the arcuate rack segment 100 and frame in a counterclockwise direction to the position in which it is shown in FIG. 2. After the coil has been conducted to the strapping station in substantially centered relationship with respect to the strap chute 70, movement of the conveyor is terminated. If the particular coil undergoing strapping is of adequate height so that the strapping head and chute can be lowered to a point where the chute 70 registers with the mid-plane of the coil, strapping operations may be commenced immediately. However, if the coil is of inadequate height, such as is the coil C shown in FIG. 2, fluid will be supplied to the lower port 116 of the piston and cylinder assembly 109, thus projecting the plunger 112, and consequently the coil-supporting platform 110 to its uppermost position. Since the platform directly underlies the coil C, the coil will thus be elevated to a final strapping position wherein the jib 341 and its associated strapping instrumentalities including the strapping head 80 and strap chute 70 may be lowered into register with the mid-plane of the coil. Such lowering of the strapping instrumentalities is effected by supplying fluid to the upper port 44 of the piston and cylinder assembly 41 to thus lower the carriage 30 and jib 34.

Prior to such lowering of the jib 34, fluid is supplied to the innermost manifold connection 138 for the two cylinders 132, thus projecting the plungers 130 and causing the strap-supporting arms 122 to be swung inwardly in unison toward the coil C until such time as the rollers 124 make contact with the outermost winding of the coil. At the same time fluid is fed to the fluid port 96 of the cylinder 90 to thus retract the carriage 82 and thus bring the strapping head into operative register with the opposed ends 72 and 74 of the strap chute so that the strapping material may be fed into and through the chute 70 in the usual manner of strapping operations as exemplified in U.S. Pat. No. 2,915,003, heretofore mentioned.

After the strapping loop has been established by the chute 70, fluid is supplied to the upper port 44 of the cylinder 42, thus lowering the jib 34, and consequently the strapping head 80 and chute 70 (now filled with the strapping loop), into register with the midplane of the coil C. Thereafter, fluid is supplied to the port 98 of the cylinder 90 so as to draw the strapping head 80 inwardly toward the coil C and bring the same into actual contact therewith. At the same time, and while the cylinder remains effective, operation of the strapping head is resumed and tensioning of the strapping loop takes place in the usual manner, thus drawing the loop into firm frictional contact with the outermost winding of the coil. As this tensioning operation commences, the strapping loop shrinks in diameter and is thus drawn inwardly or stripped, so to speak, from the channel-shaped strap chute where its downward movement is arrested by the two arms 122 which now are in engagement with the coil. Continued tensioning of the strapping loop then serves to take up the slack existing in the loop until such time as the strapping is drawn into firm frictional engagement with the outermost coil winding.

[t has previously been set forth how hot sheet metal strip coils emerge from the rolling mill operation in a loose condition with their outermost few coil turns not securely wound on the inner solid portions of the coil. in order to tighten these outermost coils according to the present invention, the final strap tensioning operation is accompanied. by rotation of the frame 56 in a clockwise direction as viewed in H6. 2, thus causing the strapping head to describe an are about the axis of the coil C and in a coil tightening direction. The frictional grip of the strapping loop during its final tensioning operation is relied upon to shift the outermost coil turn circumferentially until such time as all looseness in the coil has been effectively taken up. It has been ascertained that a circumferential shifting of the outermost coil turn throughout an arc ofapproximately is adequate to tighten any given strip coil which may be encountered and, accordingly, the stroke of the frame 56 as determined by the effective length of the toothed arcuate rack is designed accordingly. Where a given coil becomes fully tightened before the rack ,lltlll has been traversed by the pinion 106, the motor M will stall.

After the looseness in the coil has thus been taken up, the strapping head 80 continues its cycle during which time a seal is applied to the overlapping portions of the strapping loop and the free end of the strapping is severed from the loop, all in the usual manner of strapping machine operations as exemplified by the aforementioned U.S. Pat. No. 2,915,003.

During the strap tensioning operation, the strapping material which encircles the coil assimilates the residual heat of the coil so that as the coil shrinks in diameter during subsequent cooling thereof, the strap loop which encircles the same will likewise shrink without loss of tension.

When the strapping operation has been completed as described above, fluid is applied to the lowermost port 45 of the cylinder 42 as well as to the uppermost port 116 of the cylinder 1 14, thus raising the jib 34 and lowering the platform so as to restore the coil C to the conveyor 10, at which time adequate clearance is afforded by the strap chute so that the coil may be conducted by the conveyor from the strapping station S.

It will be understood, of course, that the sequence of operations described above may be varied to accommodate the exigencies of different coil heights and diameters, as well as to satisfy the preference of individual operators. Although no particular operation of the various fluid actuated cylinders 42, 90, 114 and 132 has been indicated, it is apparent that these cylinders may be operated by pneumatic or hydraulic fluid under the control of suitable automatic or semiautomatic sequencing or timing mechanism. It is possible for an operator to individually operate the various cylinders by the selective admission of fluid thereto. With a coil of relatively large height, the platform raising operation may be omitted and the strapping head and strap chute may be lowered into register with the mid-plane of the coil. Restoration of the jib 34 to its full vertical height will usually be effected after each coil strapping operation for coilclearance purposes during movement of the strapped coil away from the strapping station. However where extremely short coils, such as the coil C1 indicated by the dotted outline in F IG. 1, the carriage 32 may be permanently maintained at the appropriate strapping level where ground clearance for the strapping load affords no problem and the platform 110 relied upon solely for attaining registry of successive coils with the strap chute 70 at the strapping station. Additionally, movement of the horizontally shiftable carriage 82 radially outwardly away from the strapped coil may be effected at any time after the strapping head operations have terminated. Preferably it will be effected prior to elevation of the main jib-supporting carriage 32. i

The invention therefore is not to be limited to the exact sequence of operations or to the precise arrangement of parts shown in the accompanying drawings or described in this specification as various changes in the details of construction may be resorted to without departing from the spirit of the invention.

We claim:

1. in an apparatus for tensioning a loop of strapping about a vertically disposed sheet metal coil while simultaneously tightening the coil turns, in combination, a coil support, a frame disposed above the level of a coil on said support and rotatable about the vertical axis of the coil, an arcuate strap chute fixedly suspended from said frame for reception of strapping endwise to provide said loop, said frame and support being capable of relative vertical movement with respect to each other to bring the strap loop in encircling relation to the coil, a carriage mounted on said frame for radial shifting movement toward and away from the coil axis, a strapping head fixedly suspended from the carriage at the level of the chute and embodying means for feeding strapping to the chute and means for tensioning the strapping loop formed by the chute, power means for moving the carriage from an outer position where the head feeds strapping to the chute to an inner position where the head bears against the coil and where the tensioning means draws the strapping loop from the chute and tight against the coil, power means for rotating the frame, the chute and carriage supported thereby bodily as a unit in a coil-tightening direction while said tensioning means maintains the loop tight against the coil, and power means for effecting relative vertical movement between the frame and support.

2. The combination set forth in claim 1, wherein said power means for effecting relative vertical movement between the frame and support comprises a fluid-actuated hoist for the support whereby a coil of relatively short height may be raised and thus projected into the confines of the strap chute.

3. The combination set forth in claim 2, wherein said power means further includes a fluid-actuated hoist for the frame.

4. The combination set forth in claim 1, wherein said power means for moving the carriage from its outer position to its inner position comprises a fluid piston and cylinder assembly effective between the frame and head to maintain the latter yieldingly pressed against the coil during the tensioning and frame-rotating operation.

5. In an apparatus for repeatedly tensioning a loop of strapping about successive sheet metal coils disposed at a strapping station while simultaneously tightening the coil turns, in combination, a horizontal conveyor for conducting successive coils to the strapping station at a receiving level, a vertically shiftable coil support disposed beneath said receiving level and in register with the conveyor for elevating the coils to a desired strapping level, a column support positioned adjacent the strapping station, a jib-supporting carriage slidable vertically on said column support, a jib projecting horizontally from said carriage and overlying the strapping station, a bearing support at the outer end of said jib, a frame carried by said bearing support for rotation in a horizontal plane about the axis of a coil disposed on said coil support, an arcuate strap chute fixedly suspended from said frame for reception of strapping endwise to provide said loop, a strapping headsupporting carriage mounted on said-frame for radial shifting movements toward and away from said axis at the level of said chute, means for selectively effecting vertical shifting movements of the coil-support and jib-supporting carriage to effect relative vertical movement therebetween to bring the strap chute and coil into horizontal register at a desired strapping level, a strapping head fixedly suspended from the carriage at the level of the chute and embodying means for feeding strapping to the chute and means for tensioning the strapping loop formed by the chute, power means for moving the strapping head-supporting carriage from an outer position where the head feeds strapping to the chute to an inner position where the head bears against the coil and where the tensioning means draws the strapping loop from the chute and tightagainst the coil, and power means for rotating the frame, the chute and the carriage supported thereby bodily as a unit in a coil-tightening direction while said tensioning means maintains the loop tight against the coil. 1 

